/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xalan.templates;

import org.xml.sax.SAXException;

import javax.xml.transform.TransformerException;

import wx.xml.xalan.xalan.res.XSLTErrorResources;
import wx.xml.xalan.xalan.transformer.TransformerImpl;
import wx.xml.xalan.xml.dtm.DTM;
import wx.xml.xalan.xml.serializer.SerializationHandler;
import wx.xml.xalan.xpath.Expression;
import wx.xml.xalan.xpath.XPath;
import wx.xml.xalan.xpath.XPathContext;
import wx.xml.xalan.xpath.objects.XObject;

/**
 * Implement xsl:value-of.
 * <pre>
 * <!ELEMENT xsl:value-of EMPTY>
 * <!ATTLIST xsl:value-of
 *   select %expr; #REQUIRED
 *   disable-output-escaping (yes|no) "no"
 * >
 * </pre>
 *
 * @xsl.usage advanced
 * @see <a href="http://www.w3.org/TR/xslt#value-of">value-of in XSLT Specification</a>
 */
public class ElemValueOf extends ElemTemplateElement {
    static final long serialVersionUID = 3490728458007586786L;

    /**
     * The select expression to be executed.
     *
     * @serial
     */
    private XPath m_selectExpression = null;

    /**
     * True if the pattern is a simple ".".
     *
     * @serial
     */
    private boolean m_isDot = false;
    /**
     * Tells if this element should disable escaping.
     *
     * @serial
     */
    private boolean m_disableOutputEscaping = false;

    /**
     * Get the "select" attribute.
     * The required select attribute is an expression; this expression
     * is evaluated and the resulting object is converted to a
     * string as if by a call to the string function.
     *
     * @return The value of the "select" attribute.
     */
    public XPath getSelect() {
        return m_selectExpression;
    }

    /**
     * Set the "select" attribute.
     * The required select attribute is an expression; this expression
     * is evaluated and the resulting object is converted to a
     * string as if by a call to the string function.
     *
     * @param v The value to set for the "select" attribute.
     */
    public void setSelect(XPath v) {

        if (null != v) {
            String s = v.getPatternString();

            m_isDot = (null != s) && s.equals(".");
        }

        m_selectExpression = v;
    }

    /**
     * Get the "disable-output-escaping" attribute.
     * Normally, the xml output method escapes & and < (and
     * possibly other characters) when outputting text nodes.
     * This ensures that the output is well-formed XML. However,
     * it is sometimes convenient to be able to produce output
     * that is almost, but not quite well-formed XML; for
     * example, the output may include ill-formed sections
     * which are intended to be transformed into well-formed
     * XML by a subsequent non-XML aware process. For this reason,
     * XSLT provides a mechanism for disabling output escaping.
     * An xsl:value-of or xsl:text element may have a
     * disable-output-escaping attribute; the allowed values
     * are yes or no; the default is no; if the value is yes,
     * then a text node generated by instantiating the xsl:value-of
     * or xsl:text element should be output without any escaping.
     *
     * @return The value of the "disable-output-escaping" attribute.
     * @see <a href="http://www.w3.org/TR/xslt#disable-output-escaping">disable-output-escaping in XSLT Specification</a>
     */
    public boolean getDisableOutputEscaping() {
        return m_disableOutputEscaping;
    }

    /**
     * Set the "disable-output-escaping" attribute.
     * Normally, the xml output method escapes & and < (and
     * possibly other characters) when outputting text nodes.
     * This ensures that the output is well-formed XML. However,
     * it is sometimes convenient to be able to produce output
     * that is almost, but not quite well-formed XML; for
     * example, the output may include ill-formed sections
     * which are intended to be transformed into well-formed
     * XML by a subsequent non-XML aware process. For this reason,
     * XSLT provides a mechanism for disabling output escaping.
     * An xsl:value-of or xsl:text element may have a
     * disable-output-escaping attribute; the allowed values
     * are yes or no; the default is no; if the value is yes,
     * then a text node generated by instantiating the xsl:value-of
     * or xsl:text element should be output without any escaping.
     *
     * @param v The value to set for the "disable-output-escaping" attribute.
     * @see <a href="http://www.w3.org/TR/xslt#disable-output-escaping">disable-output-escaping in XSLT Specification</a>
     */
    public void setDisableOutputEscaping(boolean v) {
        m_disableOutputEscaping = v;
    }

    /**
     * Get an integer representation of the element type.
     *
     * @return An integer representation of the element, defined in the
     * Constants class.
     * @see wx.xml.xalan.xalan.templates.Constants
     */
    public int getXSLToken() {
        return Constants.ELEMNAME_VALUEOF;
    }

    /**
     * This function is called after everything else has been
     * recomposed, and allows the template to set remaining
     * values that may be based on some other property that
     * depends on recomposition.
     * <p>
     * NEEDSDOC @param sroot
     *
     * @throws TransformerException
     */
    public void compose(StylesheetRoot sroot) throws TransformerException {

        super.compose(sroot);

        java.util.Vector vnames = sroot.getComposeState().getVariableNames();

        if (null != m_selectExpression)
            m_selectExpression.fixupVariables(
                vnames, sroot.getComposeState().getGlobalsSize());
    }

    /**
     * Return the node name.
     *
     * @return The node name
     */
    public String getNodeName() {
        return Constants.ELEMNAME_VALUEOF_STRING;
    }

    /**
     * Execute the string expression and copy the text to the
     * result tree.
     * The required select attribute is an expression; this expression
     * is evaluated and the resulting object is converted to a string
     * as if by a call to the string function. The string specifies
     * the string-value of the created text node. If the string is
     * empty, no text node will be created. The created text node will
     * be merged with any adjacent text nodes.
     *
     * @param transformer non-null reference to the the current transform-time state.
     * @throws TransformerException
     * @see <a href="http://www.w3.org/TR/xslt#value-of">value-of in XSLT Specification</a>
     */
    public void execute(TransformerImpl transformer) throws TransformerException {

        XPathContext         xctxt = transformer.getXPathContext();
        SerializationHandler rth   = transformer.getResultTreeHandler();

        if (transformer.getDebug())
            transformer.getTraceManager().fireTraceEvent(this);

        try {
            // Optimize for "."
            if (false && m_isDot && !transformer.getDebug()) {
                int child = xctxt.getCurrentNode();
                DTM dtm   = xctxt.getDTM(child);

                xctxt.pushCurrentNode(child);

                if (m_disableOutputEscaping)
                    rth.processingInstruction(
                        javax.xml.transform.Result.PI_DISABLE_OUTPUT_ESCAPING, "");

                try {
                    dtm.dispatchCharactersEvents(child, rth, false);
                } finally {
                    if (m_disableOutputEscaping)
                        rth.processingInstruction(
                            javax.xml.transform.Result.PI_ENABLE_OUTPUT_ESCAPING, "");

                    xctxt.popCurrentNode();
                }
            } else {
                xctxt.pushNamespaceContext(this);

                int current = xctxt.getCurrentNode();

                xctxt.pushCurrentNodeAndExpression(current, current);

                if (m_disableOutputEscaping)
                    rth.processingInstruction(
                        javax.xml.transform.Result.PI_DISABLE_OUTPUT_ESCAPING, "");

                try {
                    Expression expr = m_selectExpression.getExpression();

                    if (transformer.getDebug()) {
                        XObject obj = expr.execute(xctxt);

                        transformer.getTraceManager().fireSelectedEvent(current, this,
                            "select", m_selectExpression, obj);
                        obj.dispatchCharactersEvents(rth);
                    } else {
                        expr.executeCharsToContentHandler(xctxt, rth);
                    }
                } finally {
                    if (m_disableOutputEscaping)
                        rth.processingInstruction(
                            javax.xml.transform.Result.PI_ENABLE_OUTPUT_ESCAPING, "");

                    xctxt.popNamespaceContext();
                    xctxt.popCurrentNodeAndExpression();
                }
            }
        } catch (SAXException se) {
            throw new TransformerException(se);
        } catch (RuntimeException re) {
            TransformerException te = new TransformerException(re);
            te.setLocator(this);
            throw te;
        } finally {
            if (transformer.getDebug())
                transformer.getTraceManager().fireTraceEndEvent(this);
        }
    }

    /**
     * Add a child to the child list.
     *
     * @param newChild Child to add to children list
     * @return Child just added to children list
     * @throws DOMException
     */
    public ElemTemplateElement appendChild(ElemTemplateElement newChild) {

        error(XSLTErrorResources.ER_CANNOT_ADD,
            new Object[]{newChild.getNodeName(),
                this.getNodeName()});  //"Can not add " +((ElemTemplateElement)newChild).m_elemName +

        //" to " + this.m_elemName);
        return null;
    }

    /**
     * Call the children visitors.
     *
     * @param visitor The visitor whose appropriate method will be called.
     */
    protected void callChildVisitors(XSLTVisitor visitor, boolean callAttrs) {
        if (callAttrs)
            m_selectExpression.getExpression().callVisitors(m_selectExpression, visitor);
        super.callChildVisitors(visitor, callAttrs);
    }

}
